The projected growth of the U.S. population will exert growth pressure on expensive
and expansive cities alike. There is infinite nuance in how cities can respond to
the challenge, but essentially they must situate themselves in the space defined
by three alternatives.

The first alternative is to expand with gusto. Cities that follow this path will
maintain housing at more affordable levels, thereby retaining their current social
character. However, going down this path will further entrench the ills associated
with sprawl. Today’s expansive cities are already on this path. The expensive cities
could renew their expansion, too, but it is not equally feasible for all of them
to do so because some of them – particularly on the west coast – already face natural
geographic boundaries that limit their potential to expand.

The second alternative is to avoid expansion, and maintain the status quo with respect
to densification. Going down this path will divert population growth towards more
accommodating U.S. cities (the expansive ones), and it will minimize changes to the
physical character of cities and their surrounding environment. However, it will
render housing increasingly unaffordable for a growing share of the population, and
has already set in motion a sorting process whereby, on net, the affluent migrate
into such cities while the less affluent are crowded out. In other words, it will
unequivocally change the social character of these cities, while keeping their physical
facade intact. Today’s expensive cities – including Seattle and Portland, despite
their limited success in densifying – are on this path.10

The third alternative is to enact fundamental changes to land use policy that prompt
far more substantial densification than any U.S. city has undergone to date. For
expensive cities to increase their housing production on par with expansive ones
would require a reset of land use norms. It would require cities to stop relying
on vacant lots as the primary means of densification, and embrace redevelopment instead.
For example, it would warrant the undoing of single family zoning through the permission
and incentivization of multifamily redevelopment in areas currently reserved for
single family homes. Such a change would need to be coupled with a broader acceptance
of multifamily housing as a legitimate place for raising children.11 It would also
require a leap of faith that in the chicken-and-egg conundrum of density and transportation
infrastructure, density can come first. This alternative will accommodate population
growth, and will maintain housing affordability at a level that is more expensive
than what the first alternative can achieve, but which is far more reasonable than
what the second one offers.12 As a result, it will also go a long way towards maintaining
the social character of the city. However, it will come at the cost of substantially
altering the built environment. The facade will change.

The following diagram summarizes the tradeoffs that cities face. Of course, cities
do not literally face a choice among the three alternatives. Rather, the overall
impact of the land use policy enacted by all of the governing bodies in a city is
equivalent to choosing a location within the triangle, representing a certain mix
the of three alternatives.

Is the third alternative realistic? Many grand events and changes have come about
in our lifetimes, and the introduction of substantial densification in U.S. cities
could be another. The nascent YIMBY movement and the current media uproar in reaction
to restrictive land use policy are both promising signs. Nevertheless, the third
alternative appears unlikely at this time. The control of planning decisions in the
U.S. tends to be highly dispersed, and decisions made at a more local level tend
to reject development because negatively impacted stakeholders are usually concentrated
nearby, whereas the beneficiaries are not. Moreover, the expensive cities’ current
trajectory ultimately benefits the haves, who hold more sway than the have-nots.

If we rule out the third alternative as unrealistic, then cities confronting growth
pressure face a tradeoff between accommodating growth through outward expansion,
or accepting the social implications of failing to build enough new housing. Sprawl
is not something to be welcomed. But people must understand that with neither outward
expansion nor meaningful densification, U.S. cities cannot provide enough housing
to prevent equally unwelcome changes to their social character. In the words of former
Palo Alto planning and transportation commissioner Kate Vershov-Downing, “if things
keep going as they are [the] streets will look just as they did decades ago, but
[the] inhabitants, spirit, and sense of community will be unrecognizable.”